1. Field of the Invention
The present invention relates to an improvement of a fluid pressure control device which includes: a spool valve for alternatively switching communication and disconnection of an output port with and from an input port or a release port depending on whether fluid pressure is applied to or released from a pilot chamber; and a solenoid three-way valve for alternatively switching between a condition for applying the fluid pressure to the pilot chamber from the input port, and a condition for releasing the fluid pressure from the pilot chamber.
2. Description of the Related Art
Japanese Patent Application Laid-open No. 2003-156173 and the like have already made known the following fluid pressure control device. The spool valve and the solenoid three-way valve are disposed in a valve housing such that axes of the spool valve and the solenoid three-way valve are in parallel with each other. A size of the valve housing, namely the fluid pressure control device, is reduced in a direction along the axes of these valves. In addition, a fluid pressure release passage leading to a valve chamber of the solenoid three-way valve is provided to the valve housing so as to lead to the release port of the spool valve. By these, no specialized release port needs be provided to the solenoid three-way valve side, and pipe connection can be simplified.
The conventional fluid pressure control device, however, involves a problem of an increase in manufacturing cost, because a fixed core and a solenoid housing (yoke) are formed integrally by forging and the like. In addition, because a part of a valve section and a part of a solenoid section, of the solenoid three-way valve, are integrally connected to each other, the structure of the fluid pressure control device is disadvantageous from a viewpoint of cost reduction by commonly using a configuration part of the solenoid section for a different solenoid valve (a solenoid two-way valve, for example) whose valve section has a different structure.